Picking your mates, the ones you can trust, the ones you can rely on, the ones you can banter and be honest with; these ones seem increasingly difficult to find. With the last British prime-minister appointing the first ever "Loneliness Minister", feelings of loneliness and insignificance are now being described as an epidemic. We look at the friendship portion of our relationships and try to figure out what makes for great friends, why they are important and what good they can do for us.